The Submarine Volcano Eruption off El Hierro Island: Effects on the Scattering Migrant Biota and the Evolution of the Pelagic Communities

Abstract

The submarine volcano eruption off El Hierro Island (Canary Islands) on 10 October 2011 promoted dramatic perturbation of the water column leading to changes in the distribution of pelagic fauna. To study the response of the scattering biota, we combined acoustic data with hydrographic profiles and concurrent sea surface turbidity indexes from satellite imagery. We also monitored changes in the plankton and nekton communities through the eruptive and post-eruptive phases. Decrease of oxygen, acidification, rising temperature and deposition of chemicals in shallow waters resulted in a reduction of epipelagic stocks and a disruption of diel vertical migration (nocturnal ascent) of mesopelagic organisms. Furthermore, decreased light levels at depth caused by extinction in the volcanic plume resulted in a significant shallowing of the deep acoustic scattering layer. Once the eruption ceased, the distribution and abundances of the pelagic biota returned to baseline levels. There was no evidence of a volcano-induced bloom in the plankton community.

Migrant biomass and respiratory carbon flux by zooplankton and micronekton in the subtropical northeast Atlantic Ocean (Canary Islands)

“…This fraction and other large migrant species were collected using the MOHT, a sampling device that has proved to be highly effective at capturing krill and juvenile fish (Oozeki et al, 2004;Yamamura et al, 2010). In fact, our results showed that these small organisms are an important component of migrant micronekton, which has been systematically biased in previous studies using large commercial trawls (see Wienerroither et al, 2009;Bordes et al, 2009;Ariza et al, 2014;Landeira et al, 2012). However, these studies also revealed that the MOHT sampled the adult fraction of several myctophid species and other large migrating fish poorly (e.g., Gonostoma or Chauliodus).…”

Submarine and deep-sea mine tailing placements: A review of current practices, environmental issues, natural analogs and knowledge gaps in Norway and internationally

“…There are natural analogs to the different forms of tailings disturbance described above. For example natural massive sedimentation can result from volcanic eruptions (Ariza et al, 2014), slumps, slides, debris flows and turbidity flows on margins (Masson, 1996), iceberg scouring, tectonically induced mass wasting or storm induced flows of slope or canyon sediments, flood deposits from land and benthic storms that suspend and redeposit seafloor sediments (Aller, 1989;Wheatcroft, 2000). Volcanic eruptions can deposit massive ash layers on the seafloor (Cita and Podenzani, 1980;Hess and Kuhnt, 1996).…”

Transient Changes in Bacterioplankton Communities Induced by the Submarine Volcanic Eruption of El Hierro (Canary Islands)

“…These physical-chemical anomalies had strong effects on some pelagic communities. Dead fish were observed floating on surface waters, no fish schools were acoustically detected within the affected area [ 12 ] and the diel vertical migration of zooplankton was disrupted [ 14 ]. Furthermore, preliminary results reported that the activity of the local microbial communities was also significantly altered.…”